Dr. Yasser Ahmed Abdelrahman

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EVIDENCE BASED MEDICINE

• Dr. Yasser Ahmed Abdelrahman
• Lecturer of anesthesia and intensive care
• Ain shams university, Faculty of MedicineJune,
  2012

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HYPETHESIS

• Hypo-ti-thenai To put under or Suppose

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HYPETHESIS
observation
understanding
intuition
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HYPOTHESIS TESTING
observation
understanding
intuition
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CLINICAL DECISION
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Evidence-based medicine is the integration of the
best available research evidence with clinical
expertise and patient values.
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• EBM is the process of systematically reviewing,
  appraising and using clinical research findings
  to aid the delivery of optimum clinical care to
  patients

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Steps to deliver optimal clinical care

1. Production of evidence.
2. Production of guidelines.
3. Implementation of guidelines.
4. Evaluation of compliance.

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Steps in Practicing EBM

1. Convert the need for information into an
   answerable question.
2. Track down the best evidence with which to answer
   that question.
3. Critically appraise the evidence for its
   validity, impact, and applicability.
4. Integrate the evidence with our clinical
   expertise and our patients characteristics and
   values.

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Developing clinical questions
To get the right answer, you must first ask the
right question.
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Developing the clinical question

• Step 1 Formulate the clinical issue into a
  searchable, answerable question.
• Step 2 Distinguish what type of question you
  may have.

Background
Foreground
Experience with Condition
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Background questions

• Background questions ask for general information
  about a condition or thing.
• A question root (who, what, when, etc) combined
  with a verb.

What modes of ventilation can cause barotrauma?
Background questions are typically answered by
textbooks.
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Foreground questions

• Foreground questions ask for specific knowledge
  about a specific patient with a specific
  condition.

Is APRV protective against barotrauma in patients
with ARDS?
Foreground questions are typically answered by
databases that access the research literature
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Differences in Type of ?s
General
Specific

• Background question composed of question
  modifier and condition.
• Cover the full range of biologic, psychologic, or
  sociologic aspect of human illness
• Can be answered by reference works.
• Can be used as a trampoline for generating
  specific questions to be answered by EBM.

• Foreground question composed of patient and/or
  problem, intervention (therapy, diagnostic test,
  etc.), comparison and outcome.
• Often requires more comprehensive and intensive
  search strategies (not necessarily more time
  consuming).
• Suitable to answering using the techniques of EBM.

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Formulate A Foreground Clinical Question

• Formulate three part question
• (P) The patient population or the problem the
  patient is suffering from
• (I) The intervention and/or (C) comparison
• (O) The outcome

(PICO)
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Types of Questions

• Diagnosis How to select a diagnostic test or
  how to interpret the results of a particular
  test.
• Prognosis What is the patient's likely course
  of disease, or how to screen for or reduce risk.
  
• Therapy Which treatment is the most effective,
  or what is an effective treatment for a
  particular condition.
• Harm or Etiology Are there harmful effects of a
  particular treatment, or how these harmful
  effects can be avoided.
• Prevention How can the patient's risk factors
  be adjusted to help reduce the risk of disease?
• Cost Looks at cost effectiveness, cost/benefit
  analysis.

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Question
Templates for Asking PICO QuestionsTherapyIn
__________________, what is the effect of
____________________ on ______________________
compared with __________________?EtiologyAre
______________ who have _________________ at
________________ risk for/of ____________________
compared with _____________________
with/without ______________________?Diagnosis
or Diagnostic TestAre (Is) ______________________
___ more accurate in diagnosing ________________
compared with ________________?PreventionFor
_________________ does the use of _______________
reduce the future risk of ________________
compared with _________________?PrognosisDoes
_______________ influence _________________ in
patients who have __________________?
Melnyk, B. M., Fineout-Overholt, E. (2005).
Evidence-based practice in nursing healthcare
A guide to best practice. Philadelphia, PA
Lippincott Williams Wilkins.
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Well Formulated ?s

• Focus scarce learning time on evidence directly
  relevant to patients needs and our particular
  knowledge needs.
• Suggest high-yield search strategies.
• Help us to model life-long learning techniques
  for our colleagues and students.
• Are answerable and, thus, reinforce the
  satisfaction of finding evidence that makes us
  better, faster clinicians.

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Steps in Practicing EBM

1. Convert the need for information into an
   answerable question.
2. Track down the best evidence with which to answer
   that question.
3. Critically appraise the evidence for its
   validity, impact, and applicability.
4. Integrate the evidence with our clinical
   expertise and our patients characteristics and
   values.

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Track down the best evidence

• Ask your librarian
• Use search engine

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Medical literature

• Primary original research
• Experimental (an intervention is made or
  variables are manipulated)
• Randomized Control Trials
• Controlled trials
• Observational (no intervention or variables are
  manipulated)
• Cohort studies
• Case-control studies
• Case reports

• Secondary reviews of original research
• Meta-analysis
• Systematic reviews
• Practice guidelines
• Reviews
• Decision analysis
• Consensus reports
• Editorial, commentary

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Evidence Pyramid
Meta-analysis
Systematic Review
Randomized Controlled Trial
Cohort Studies
Case Control Studies
Case Series/Case Reports
Animal Research
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• STUDY DESIGN APPROPRIATE TO OBJECTIVES

Cause
Prevalence
Therapy
Prognosis
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Type of Question Suggested Best Type of Study
Therapy RCT gt cohort gt case control gt case series
Diagnosis Prospective, blind comparison to gold standard
Etiology / Harm RCT gt cohort gt case control gt case series
Prognosis Cohort study gt case control gt case series
Prevention RCT gt cohort study gt case control gt case series
Clinical Exam Prospective, blind comparison to gold standard
Cost Economic analysis
Questions of therapy, etiology and prevention which can best be answered by RCT can also be answered by a meta-analysis or systematic review. Questions of therapy, etiology and prevention which can best be answered by RCT can also be answered by a meta-analysis or systematic review.
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Levels of evidence

• Level I
• obtained from at least one properly controlled
  randomized trial, considered the gold standard of
  evidence.
• Level II-1
• derived from controlled trials without
  randomization.
• Level II-2
• well-designed cohort or case-control studies.
• Level II-3
• includes studies with external control groups or
  ecological studies.
• Level III
• evidence is derived from reports of expert
  committees, not because it is weaker than levels
  I or II, but because it is often difficult to
  ascertain the scientific origin of the committee
  opinion.

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Levels of Evidences

• (I-1) a well done systematic review of 2 or more
  RCTs
• (I-2) a RCT
• (II-1) a cohort study
• (II-2) a case-control study
• (II-3) a dramatic uncontrolled experiment
• (III) respected authorities, expert committees,
  etc..
• (IV) ...someone once told me....
• http//www.phru.org/casp/
• See also AAFP

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IMRAD format

• Introduction why the authors decided to conduct
  the research.
• Methods how they conducted the research and
  analyzed their results.
• Results what was found.And
• Discussion what the authors think the results
  mean.

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PP-ICONS

• Problem
• Patient or population
• Intervention
• Comparison
• Outcome
• Number of subjects
• Statistics

Flaherty, Robert J. A simple method for
evaluating the clinical literature. Fam Prac
Mgt, May 200447-52. Available online at
http//www.aafp.org/fpm/20040500/47asim.html.
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Steps in Practicing EBM

1. Convert the need for information into an
   answerable question.
2. Track down the best evidence with which to answer
   that question.
3. Critically appraise the evidence for its
   validity, impact, and applicability.
4. Integrate the evidence with our clinical
   expertise and our patients characteristics and
   values.

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Critical Appraisal

• STUDY DESIGN APPROPRIATE TO OBJECTIVES
• STUDY SAMPLE REPRESENTATIVE
• CONTROL GROUP ACCEPTABLE
• QUALITY OF MEASUREMENTS AND OUTCOMES
• COMPLETENESS
• DISTORTING INFLUENCES

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Critical Appraisal

• STUDY SAMPLE REPRESENTATIVE
• Source of sample
• Sampling method
• Sample size
• Entry criteria and exclusion
• Non-respondents

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Critical Appraisal

• STUDY DESIGN APPROPRIATE TO OBJECTIVES
• STUDY SAMPLE REPRESENTATIVE
• CONTROL GROUP ACCEPTABLE
• QUALITY OF MEASUREMENTS AND OUTCOMES
• COMPLETENESS
• DISTORTING INFLUENCES

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Critical Appraisal

• CONTROL GROUP ACCEPTABLE

• Definition of controls
• Source of controls
• Matching and randomization
• Comparable characteristics

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Critical Appraisal

• STUDY DESIGN APPROPRIATE TO OBJECTIVES
• STUDY SAMPLE REPRESENTATIVE
• CONTROL GROUP ACCEPTABLE
• QUALITY OF MEASUREMENTS AND OUTCOMES
• COMPLETENESS
• DISTORTING INFLUENCES

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Critical Appraisal

• QUALITY OF MEASUREMENTS AND OUTCOMES

• Validity
• Reproducibility
• Blindness
• Quality control

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Critical Appraisal

• STUDY DESIGN APPROPRIATE TO OBJECTIVES
• STUDY SAMPLE REPRESENTATIVE
• CONTROL GROUP ACCEPTABLE
• QUALITY OF MEASUREMENTS AND OUTCOMES
• COMPLETENESS
• DISTORTING INFLUENCES

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Critical Appraisal

• COMPLETENESS

• Compliance
• Drop outs and deaths
• Missing data

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Critical Appraisal

• STUDY DESIGN APPROPRIATE TO OBJECTIVES
• STUDY SAMPLE REPRESENTATIVE
• CONTROL GROUP ACCEPTABLE
• QUALITY OF MEASUREMENTS AND OUTCOMES
• COMPLETENESS
• DISTORTING INFLUENCES

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Critical Appraisal

• DISTORTING INFLUENCES

• Extraneous treatments
• Contamination
• Changes over time
• Confounding factors
• Distortion reduced by analysis

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Critical Appraisal

• STUDY DESIGN APPROPRIATE TO OBJECTIVES
• STUDY SAMPLE REPRESENTATIVE
• Source of sample
• Sampling method
• Sample size
• Entry criteria and exclusion
• Non-respondents
• CONTROL GROUP ACCEPTABLE
• Definition of controls
• Source of controls
• Matching and randomization
• Comparable characteristics
• QUALITY OF MEASUREMENTS AND OUTCOMES
• Validity
• Reproducibility
• Blindness
• Quality control
• COMPLETENESS
• Compliance

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Limitations

• Time.
• Shortage of coherent and consistent scientific
  evidence (therapeutic nihilism).
• Challenges of applying evidence to care of
  individual patients.
• General barriers to the practice of quality
  medicine (e.g. costs, patient expectations, etc.).

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IS EVIDENCE BASEDMEDICINE DEAD?Trisha
GreenhalghProfessor of Primary CareUniversity
College London
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• Who ask the question
• Who set the research agenda
• Who say RCTs are objective
• Who say RCTs are generalizable
• What about clinical freedom
• What about the patient perspective
• What about the doctors hunch
• What about the service reality
• What about the political priority

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